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木质素是自然界中含量巨大的天然酚类聚合物,其总量仅次于纤维素。由于其结构复杂性,仅有不到2%的木质素用于工业生产,因此实现木质素的高效综合利用是目前该领域的难题,而木质素的氧化还原转化为芳香化合物是目前一个重要且有前景的手段:木质素氧化解聚能显著降低其主要化学键键能,促进木质素转化为香草醛、紫丁香醛和高香草醛等高度官能化的单体;而木质素还原解聚可将其结构中含氧官能团脱除,转化为低氧/无氧木质素生物油,可作为高热值生物燃油,且在反应中能显著抑制缩合反应的进行。本文简要介绍了木质素的结构单元以及联接方式,同时从反应条件和催化剂等方面全面综述了国内外木质素氧化还原解聚的最新研究进展,并对其反应机理进行了详细探讨。在此基础上,针对当前木质素解聚过程中的难题提出了未来该领域的研究重点和方向。
Lignin is a natural phenolic polymer with a large amount of natural products, second only to cellulose. Because of its structural complexity, less than 2% of lignin is used in industrial production, so it is a difficult problem in the field to achieve efficient and comprehensive utilization of lignin. The redox conversion of lignin to aromatic compounds is currently an important Promising Approaches: Lignin oxidative depolymerization can significantly reduce its primary chemical bond energy and promote the conversion of lignin to highly functionalized monomers such as vanillin, syringaldehyde and vanillin; whereas lignin reduction depolymerization can reduce The oxygen-containing functional groups in the structure are removed and converted to hypoxia / anaerobic lignin bio-oil, which can be used as high-calorie bio-fuels, and can significantly inhibit the condensation reaction during the reaction. In this paper, we briefly introduced the structural units of lignin and the coupling methods. In the meanwhile, we reviewed the latest research progress of lignin redox depolymerization at home and abroad from the reaction conditions and catalysts. The reaction mechanism was discussed in detail. On this basis, in the light of the current problems in depolymerization of lignin, the research focuses and directions in this field are proposed.